The invention relates to a method of manufacturing a dispenser cathode comprising a porous dispenser body having an emissive surface which is destined for emission during operation, in which, in a stage of the formation of the dispenser body a tungsten powder compact which comprises an oxide of a metal at least in a surface layer is provided, the compact being subjected to an impregnation treatment with a barium-containing material to provide pores present in the compact with the metal oxide and barium containing compound for dispensing. during operation, the metal and the barium to the emissive surface.
A method of the type mentioned in the opening paragraph is disclosed in Netherlands patent application No. 8201371 corresponding to U.S. Pat. No. 4,625,142.
In this known method scandium is used as the metal and scandium oxide is provided in a surface layer of the powder volume from which the dispenser body is to be compacted. The powder volume is compacted and sintered, and the sintered compact is impregnated via a scandium oxide-free surface.
In a modified embodiment of the known method, scandium oxide is deposited on a surface of a sintered tungsten body, the body is after-firedand impregnated via a scandium oxide-free surface.
Scandium oxide may also be deposited on a body of compressed tungsten powder and the body may then be sintered and impregnated.
Although good results are obtained with scandium oxide, this material has the disadvantage of being expensive.